Generally, when lipsticks are manufactured, the cases are assembled separately from the molding of the lipstick product itself. After the assembly of the case and the molding of the stick, the holder cup is placed in the advanced position, ready to receive the lipstick product. Then the lipstick product is placed within the holder cup of the case, the holder cup is moved into the retracted position, a cover is placed on the case, and the case is ready for sale to a consumer
The means by which the stick product is held in the cup is usually via a friction fit between the stick product and the inner wall of the holder cup. These two elements, the holder cup and the stick product, are dimensioned so that a proper friction fit is obtained. The problem with this means of holding the stick product in the holder cup is that, over time, the dimensions of the stick product often will change due to a number of different causes. For example, the dimensions of stick products change due to the method of cooling of the product after molding or filling into the holder cup whereby the cooling causes product to shrink.
Also, with the increasing use of volatile ingredients within the formulations for stick products, shrinkage problems are a concern. These volatile ingredients tend to evaporate, which then causes the product to shrink, thereby causing the friction fit between the cup and the product to be insufficient to hold the product in place during a shock to the case. In either case, when this happens, a once proper fit between the holder cup and the product will no longer be sufficient to hold the product in place. Once shrinkage has occurred to the point where the fit between the holder cup and the product is insufficient to hold the product in place, a small shock to the case will cause the product to release. Once the product has released from the holder cup, it is virtually useless to the consumer.
Current holder cups try to remedy this problem in a number of different ways. Some cups provide a holder wall which protrudes from the bottom of the holder cup, so that when the stick product is inserted into the holder cup a greater surface area of contact between the product and the holder cup is provided (see DE Patent No. 3319031). Along the same premise of increasing the contact surface area, longitudinally extending internal ribs are added to the holder cup as disclosed in U.S. Pat. No. 3,175,680 and U.S. Pat. No. 4,579,134. U.S. Pat. No. 4,820,070, provides that the longitudinally extending internal ribs be a dove-tail design to further provide greater contact area and to hold the stick in place after shrinkage of the stick has occurred.
With the new formulations of stick products that contain a considerable amount of volatile ingredients, the frictional forces created by the above mentioned configurations of holder cups may not be sufficient to hold the product in place after shrinkage of the stick has occurred and then the case experiences a shock. Insufficient frictional force is available after the stick shrinks because the aforementioned holder cups all pre-form grooves within the stick product when the stick is inserted into the holder cup. The product then shrinks away from the pre-formed grooves, thereby lessening the contact surface and the frictional forces.
WO 9632031 provides for a holder cup that employs the use of a spike which penetrates a lipstick to hold the lipstick in place. This spike is either attached to a snap-ring or an arm. Both embodiments allow the spike to pass through an aperture in the holder cup, thereby puncturing a lipstick. This type of holder cup is effective in holding a stick product in place after shrinkage because a groove is not formed when the product is inserted into the holder cup. However, these embodiments require additional assembly or may be difficult to manufacture via known holder cup molding techniques.
U.S. Pat. No. 5,560,727 discloses the use of spring elements provided on the lipstick holder to aid in holding the lipstick mass in place. These spring elements are pressed into the lipstick to form rear-engaging lugs as the lipstick holder is retracted into the case. The disadvantage of this arrangement is that the rear-engaging lugs do not lock in place after they are pressed into the lipstick.
An alternative configuration holder cup is one which utilizes horizontal ribs in order to assist in securing the mass within the cup. This type of holder cup, however, also requires the use of new machinery and manufacturing methods. With the traditional method of manufacture for a longitudinal ribbed cup, the stick product is heated and poured into a mold of the desired shape. After the stick has cooled and sufficiently solidified, the stick is removed from the mold and placed within the holder cup of a pre-assembled case. When using a horizontal ribbed cup, instead of first filling the stick product within a separate mold, the stick is molded within the holder cup itself and then the case is assembled around the stick. This modified method of manufacture and assembly requires the enormous expense of the purchase of new machinery and the retraining of personnel. If, however, the stick was molded and subsequently inserted into a holder cup with horizontal ribs, assembly of the salable product would be impossible without destroying or substantially deforming the stick product. Moreover, after the stick is deformed by the horizontal ribs, a frictional force sufficient to hold the stick within the cup upon a shock to the case is not likely to be obtained.
The purpose of the present invention is to provide a stick product case which will secure the stick product in place when the case is exposed to a shock.
Another purpose of the present invention is to provide a stick product case that is simple to manufacture.
Another purpose of this invention is to provide a stick product case which will continue to hold a stick product in place even after the product changes its dimensions.
Further, it is a purpose of this invention to provide a stick product case which is a relatively simple device that avoids interference with package aesthetics.